Pfizer COVID-19 booster dose authorized by Health Canada for all adults 18+ Dubé said that for the time being, the province doesn’t plan on extending its offer of a booster shot to younger age groups because it’s not necessary.“We have no evidence of diminished immunity in this large group,” he said.The only exception will be for people who received two doses of the AstraZeneca vaccine.“Experts are recommending a booster with an mRNA vaccine, so Pfizer or Moderna, for maximum protection,” Dubé said, stressing the safety and efficacy of all vaccines.“I want to reassure the population, it’s not because there is worry regarding the Astra Zeneca, it’s really just to ensure longer protection.” Quebec suspending unvaccinated health.